How can I verify tokens created in these two different applications?

I have recently developed a website using a Regular Web Application.

I would like to call this website from Flutter’s Web View, so I created a Native application and successfully implemented login functionality.

To account for instances when users are not logged in on the website, I pass the access token obtained natively to a special URL and retrieve the user information via the API (/userinfo). Once the user is retrieved, they are logged in using those credentials.

However, an issue arose.

This website actually has an API that restricts access by verifying the access_token. The API (/userinfo) has a limit on the number of accesses per hour, and frequent accesses result in errors.

How can I verify tokens created in these two different applications?

I’m facing challenges because the access_token created in Native doesn’t match the token from the Regular Web.

I hope this translation conveys your message accurately and politely.